JP2007035147A - Method and apparatus for detecting phase error information in multilevel recording / reproducing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect phase error information and generate a reproduction clock without inserting a special recording pattern for detecting a phase error in a recording area in multi-value information reproduction.
In a multi-value information reproducing method, an ideal value between cells and a slope near the ideal value are derived in advance.
Detecting one inter-cell value in two or more consecutive cells in the recording area and two or more cell center values sandwiching the inter-cell, and the difference between the detected inter-cell value and the inter-cell ideal value; A multilevel information reproduction method for acquiring phase error information of the reproduction signal based on the inclination.
[Selection] FIG.

Description

  The present invention relates to an optical information recording / reproducing method and apparatus for recording / reproducing multi-value information, in which information pit levels are recorded or reproduced using three or more values, and more particularly to generation of a reproduction clock during reproduction from recorded information. It is related with the detection method of the phase error information for.

  In recent years, the optical memory industry has been expanding, and it has been developed from read-only CDs and DVDs to write-once using metal thin films and dye-based recording materials, as well as rewritable using magneto-optical materials and phase change materials. Its application is expanding from consumer to external memory of computers.

  Research and development for further increasing the recording capacity has been underway. As a technique for miniaturizing a light spot related to information recording / reproduction, the wavelength of a light source is changing from red (650 nm) to blue-violet (405 nm). The numerical aperture of the objective lens is also being increased from 0.6 or 0.65 to 0.85. On the other hand, more efficient multilevel recording / reproducing techniques using the same light spot size have also been proposed.

  For example, as a method of multilevel recording / reproducing technology, in Japanese Patent Laid-Open No. 5-128530, the length of an information pit in the track direction and a track for a reproduction light spot of the information pit are recorded on an information track of an optical information recording medium. Combination of direction shift amount. As a result, the multi-value information is recorded based on the correlation between the detection signal obtained from the light spot and the detection method obtained in advance when the multi-value information recording pit and the multi-value recorded information pit are reproduced. A reproduction method for reproduction has been proposed (Patent Document 1).

  In addition, a blue-violet light source (405 nm) and an optical system of NA 0.65 were used in ISOM2003 (Write-once Disks for Multi-level Optical Recording: Proceedings Fr-Po-04), which is an international conference in research on the optical disc field. For an optical disk with a track pitch of 0.46 μm, the width in the track direction of an area (hereinafter referred to as a cell) for virtually recording one information pit is set to 0.26 μm, and multilevel of 8 levels. An announcement has been made on recording and reproduction (Non-Patent Document 1).

  For example, as shown in FIG. 14, the length of the cell in the track direction (A direction in the figure) is equally divided into 16 (16 channel bits), and no information pit is recorded at level 0. do not do. Level 1 is 2 channel bits wide. Level 2 is 4 channel bits wide. Level 3 is 6 channel bits wide. Level 4 is 8 channel bits wide. Level 5 is 10 channel bits wide. Level 6 is 12 channel bits wide. Level 7 is 14 channel bits wide.

  The information pits selected in this way are recorded at random, and the amount of reflected light is received by a photodetector. Then, when the timing of sampling the reproduction signal from the obtained multilevel information pit is set when the center of the light spot comes to the center of the cell track direction, the amplitude of the reproduction signal for each level is as shown in FIG. Distribution is obtained.

  At this time, a clock for sampling information is generated in a phase-locked loop circuit (PLL circuit) by detecting phase error information by reproducing a predetermined pattern inserted at predetermined intervals in the recorded information. I'm taking it.

  FIG. 16 shows a pattern insertion example for phase error detection. In the figure, A) to I) indicate recording information strings. A) is a pattern for pulling in the PLL positioned at the head of the recording data, and this pattern is often used regardless of multi-value recording. B) is a recording pattern for learning to obtain a reproduction signal of a known pattern described below. In C), E), and G), user information to be recorded is generated by performing processing such as error correction. D), F), and H) are recording patterns for detecting a phase error of the generated clock. For example, an edge is extracted by binarization processing using a level slice, phase error information between the edge and the recovered clock is detected by a phase comparator, and is used for PLL processing of the recovered clock. In multi-level recording, the edge period is constant regardless of the recording mark size. Therefore, in order to obtain phase information with a high S / N ratio, the minimum / maximum levels appear alternately in the phase error detection pattern. It is desirable to adopt such a pattern.

  Returning to the explanation of FIG. 15, the reproduction signal level when the level 0 in which no information pits are written continues “1”, and the reproduction signal level when the level 7 information pits are continuously recorded. It is standardized as “0”.

  The value of the reproduction signal corresponding to each level has a width because it receives an influence (intersymbol interference) from information pits written before and after the information pit of interest. If the adjacent level and the reproduction signal amplitude distribution overlap as shown in FIG. 15, separation detection cannot be performed with a fixed threshold.

In the example of the announcement of ISO2003, in order to solve this, a reproduction signal from a pit row in which the value of the information pit being noticed and the information pit values before and after the information pit is known is read and stored ( Learning). A method is described in which a reproduction signal from an actual information pit is compared with a recorded value (correlation is seen) to detect separation. In this method, the recording density is approximately 16 Gbit / inch ² .
Japanese Patent Laid-Open No. 5-128530 ISOM 2003 (Write-once Disks for Multi-level Optical Recording: Proceedings Fr-Po-04)

  However, according to the multilevel information recording / reproducing method, in the reproduction clock generation for detecting the reproduction signal level, at a predetermined interval, a predetermined length such that the phase error signal can be obtained with sufficient accuracy, and For example, it is necessary to insert a sufficiently large mark row so that phase information can be detected by binarization using a fixed slice.

  The insertion of these mark rows for phase error detection has the disadvantage that the information efficiency of the recording format is lowered, the improvement of the linear density in multi-value recording is sacrificed, and the improvement of the linear density is hindered.

  The present invention has been made in view of such circumstances, and its purpose is to detect phase error information for generating a reproduction clock from a recorded information reproduction signal without inserting a special recording pattern for phase error detection. Another object of the present invention is to provide a multilevel information reproduction method that enables generation of a reproduction clock.

  The above-mentioned subject is achieved by the following.

Virtually spaced cells are provided on the track of the optical information medium,
By using a light spot to record multi-value information by changing the length of the information pit in the track direction or the area of the information pit in the cell, and detecting the level of the multistage reproduction signal from the information pit In an optical information reproducing method for reproducing multi-value information with respect to an optical information medium having a recording / reproducing area for reproducing multi-value information,
Detecting one inter-cell value in two or more consecutive cells in the recording / reproducing area, and two or more cell center values sandwiching the cell;
Based on the difference between the detected inter-cell value and the detected inter-cell ideal value corresponding to the detected cell center value, and the gradient of the reproduction signal in the vicinity of the inter-cell ideal value,
And a step of acquiring phase error information of the reproduction signal.

  According to the present invention, in an optical information recording / reproducing method and apparatus for recording / reproducing multi-value information, the level of information pits is recorded or reproduced using a value of three or more values. It is possible to detect phase error information for generating a reproduction clock directly from a reproduction signal of recorded information without providing a pattern.

  Next, the best mode for carrying out the invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of an embodiment of an optical information recording / reproducing apparatus according to the present invention.

  The optical information recording / reproducing apparatus 1 includes a control circuit 2, a spindle motor 3, an optical disk 4, an optical head 5, an optical head control circuit 6, an information recording circuit 7, an information reproducing circuit 8, a spindle motor controller 9, and an interface controller 10. .

  The control circuit 2 controls transmission / reception of information to / from an information processing apparatus such as an external computer, controls information recording / reproduction with respect to the optical disc 4 using the information recording circuit 7 and the information reproduction circuit 8, and other Control the working part. The information recording circuit 7 records multi-value information as will be described later, and the information reproduction circuit 8 reproduces multi-value information.

  The spindle motor 3 is controlled by the spindle motor controller 9 and drives the optical disk 4 to rotate. The optical disk 4 is an optical information recording medium that is inserted into or ejected from the optical information recording / reproducing apparatus 1 by a mechanism (not shown).

  The optical head 5 optically records information on the optical disk 4 and reproduces it. For the optical head 5, for example, if the wavelength of the light source is 405 nm and the numerical aperture of the objective lens is 0.85, the size of the light spot is approximately 0.405 μm. The track pitch of the optical disk 4 is 0.32 μm. The optical head control circuit 6 controls the position of the light spot by the optical head 5, and performs auto tracking control, seek operation control, and auto focusing control.

  The information reproduction circuit 8 is responsible for generating the phase error signal in information reproduction according to the present invention.

  First, a multi-value information recording method and apparatus will be described.

  FIG. 2 is a diagram for explaining the width in the track direction (A direction in the figure) due to the difference in the level of the multilevel information pit used in the optical information recording / reproducing apparatus of the present invention. For convenience of explanation, the width of the information pit in the direction perpendicular to the track direction is shown smaller than the actual width.

In the figure, a region between two thick solid lines indicates a cell. In this embodiment, since the size of the light spot is about 0.405 μm and the track pitch of the optical disk is 0.32 μm, the surface density of about 30 Gbit / inch ² can be achieved when the cell width is about 0.2 μm. Therefore, the description will be continued here assuming that the cell width is 0.2 μm.

  In this case, the width of the shortest information pit (level 1) is 25 nm, level 2 is 50 nm, level 3 is 75 nm, level 4 is 100 nm, level 5 is 125 nm, level 6 is 150 nm, and level 7 is 175 nm. It has become. Level 0 is a state in which nothing is recorded.

  This method is 8-level recording, and 3 bits can be recorded in one cell. For example, for 3-bit information, as shown in FIG. 2, (0, 0, 0) is 0 level, (0, 0, 1) is 1 level, and (0, 1, 0) is 2 (0, 1, 1) is 3 levels, (1, 0, 0) is 4 levels, (1, 0, 1) is 5 levels, (1, 1, 0) is 6 levels, (1, 1 , 1) correspond to 7 levels. Of course, other corresponding methods may be used.

  FIG. 3 shows a relationship between the light spot 13 and a schematic diagram when random information pits 12 are recorded on the track 11 on the optical disk 4. For example, when a phase change material is used as a recordable and erasable recording material, the optical spot 4 is irradiated with a light spot 13 to adjust the light quantity and timing of each of the recording pulse, erasing pulse, and cooling pulse. Thereby, the shape of the information pit is changed, and information pits having a plurality of reproduction levels are formed. In FIG. 3, it is shown as a rectangular information pit for convenience. Also, it shows how the length in the track direction is changed, but if it corresponds to the area of each level, it is not a rectangular information pit, it is a circle, an ellipse, or an arrowhead type mark Even if it exists, the essence of this proposal does not change.

  In addition to the phase change material, a magneto-optical material can be used as the recording material that can be erased. In this case, in the optical information recording / reproducing apparatus described above, the information pit shape is changed by cooperative work with a magnetic field from a magnetic head (not shown) other than the light spot, and information pits having a plurality of reproduction levels are formed.

  Furthermore, it is also possible to apply a recording material that can be additionally written, and an organic dye or a metal film can be used as the recording material. By irradiating the optical spot with an optical spot and adjusting the recording light quantity and timing thereof, the shape of the information pit is changed, and information pits having a plurality of reproduction levels are formed. Similarly, even in a read-only recording medium, information pits can be formed on a substrate as uneven shapes called phase pits, and multi-level recording is performed by modulating the area of the phase pits or the optical depth of the phase pits. Is possible.

  In order to increase the storage capacity, it is necessary to reduce the size of the cell. If it is reduced, information pits of 2 to 3 cells are included in the light spot 13 as shown in FIG. The principle of the present embodiment will be described with an example in which a phase change material is used on the premise of such multilevel recording.

  In FIG. 3, the direction of arrow A similarly indicates the track direction, and 11 indicates a track on the optical disk on which information pits are recorded. Each cell is virtually provided with a region delimited by a broken line, and information pits corresponding to the number of levels described in the upper portion are recorded as 12 according to the method of FIG. Reference numeral 13 denotes a light spot.

In this embodiment, the cell width is 0.2 μm with respect to the light spot size of about 0.405 μm. With this scale, the surface density is improved by about 1.5 times compared to the surface density of about 19.5 Gbit / inch ² when the conventional method of binary level (for example, 1-7PP modulation, 2T = 139 nm) is used. Is possible.

  Next, the result of optical simulation of the reproduction signal by this method will be described.

  FIG. 4 shows parameters used for the optical simulation. The track pitch is 0.32 μm. The size of the light spot is 0.405 μm (wavelength 405 nm, numerical aperture of objective lens: NA 0.85). The cell size is 0.2 μm. The shape of the given information pit was as shown in FIG. 2 and given to each level as shown in FIG.

  FIG. 6 shows eight consecutive levels combined in three consecutive cells (all combinations are 8x8x8 = 512), and reproduction when the light spot is moved from the first cell center to the third cell center. The signal (the amount of reflected light) was calculated.

  In the lower diagram of FIG. 6, eight combinations of cell levels (0, 1, 6) to (7, 1, 6) are shown as examples (all levels except for three cells are set to 0 level).

  In the figure, the positions of the three solid lines indicate the reproduction signal (cell median value) when there is a light spot at the center of each cell, and the positions of the two broken lines have a light spot at the boundary between the cell and the following cell. The reproduction signal (inter-cell value) in this case is shown.

  In the figure, when attention is paid to the reproduction signal (inter-cell value) at the boundary between adjacent cells, it can be seen that the inter-cell value at the boundary between the right cell and the middle cell takes almost the same value. In other words, if the combination of the left and right levels is the same (in this case, “1” and “6”), the inter-cell value is greatly affected, regardless of the level outside (in this case, the left cell). It can be seen that the effect of intersymbol interference is negligible.

  FIG. 9 shows the positional relationship when the light spot comes to the boundary between the left and right cells. For a light spot size of 0.405 μm, the width of two cells is 0.4 μm, and most of the light spots are on the left and right cells. That is, it can be intuitively understood that there is almost no influence from the outside.

  The left diagram of FIG. 8 shows the amplitude distribution of the reproduction signal of the inter-cell value for the left and right cell combinations (all combinations are 8 × 8 = 64). Here, the horizontal axis represents the sum of the left and right cell levels. That is, it can be classified into 15 values from 0 value of (0, 0) to 14 values of (7, 7).

  It can be seen that the signal is separated into 15 values from 0 to 14 without adding signal processing such as waveform equalization. The right and left cell level combinations corresponding to the 15 values are shown on the right side.

  Next, the phenomenon that is the principle of the present invention will be described based on the characteristics of the reproduced signal.

  In FIG. 6, paying attention to the signal level change of the cell center value-inter-cell value-cell center value, in addition to the good separation of the signal level from the inter-cell value, the signal change gradient is almost constant in the vicinity of the inter-cell value. It can be understood together.

  From this, if the multilevel level value of the cell center value that precedes and follows the inter-cell value is determined, the inter-cell value in the ideal state can be estimated. At the same time, it is possible to estimate the gradient of the reproduction signal in the vicinity of the intercell value. In this case, by utilizing this phenomenon, the phase error information is obtained from the reproduced signal itself. In this case, since it is necessary to sample both the cell center value and the inter-cell value, the reproduction clock needs to be at least twice as fast as the cell period.

  Further description will be given with reference to FIG. In the figure, an example of the combination of (1, 6) corresponding to the latter two values of FIG. 6 is shown for the state of the cell center value, and the time k is the reproduction signal sampling state (A ). Here, PLL control for obtaining a recovered clock is considered, and detection of phase error information in inter-cell values is considered. Assuming that the phase of the reproduction signal sampling clock is shifted to the position of k ', the detection level of the inter-cell value is (B). If the cell center value at this time is a known state of (1, 6), the ideal state of the cell center value and the inter-cell value has the relationship of (1), (6), (A) as shown in the figure, The ideal value of the intercell value and the reproduction signal gradient near the intercell value are also in a known state. Therefore, 1) the ideal reproduction signal gradient near the inter-cell value (Δv / Δt), 2) the ideal value between cells (A), 3) the inter-cell value (B) in the actual reproduction signal, and 3 points By taking this into consideration, it becomes possible to calculate the phase error state Δt ′ = [(A) − (B)] / (Δv / Δt) of the sampling clock.

  Here, the ideal state of 1) and 2) can be applied to the reproduction level obtained from the learning area of the known recording sequence provided at the head of the recording data sequence, as will be described later, in addition to the ideal state such as simulation. Rather, it can be said that the latter is preferable because it reflects various influences such as the recording state. Hereinafter, description will be added regarding the calculation of the slope of the reproduction signal near the inter-cell value and the calculation of the phase error when using the learning data.

  First, regarding the calculation of the reproduction signal gradient near the inter-cell value, the simplest example is a method of linearly approximating the values of two consecutive cell center values on the learning data and calculating the gradient near the inter-cell value. It is done. During playback, the level of the cell center value is determined. Based on this determination value, the continuous cell center value, the slope (Δv / Δt), and the inter-cell value (A) at the time of learning are derived and played back. The sampling time gap, that is, the phase error signal is detected based on the inter-cell value (B).

  Further, in the learning data, curve approximation is performed by using three values obtained by adding the values of inter-cell values located between two continuous cell center values. Then, a method of calculating the gradient (Δv / Δt) in the vicinity of the inter-cell value from the tangential gradient in the inter-cell value (A), or the curve approximation curve itself is applied as the gradient curve. By this application, it is possible to calculate the phase error signal with higher accuracy from the difference between the inter-cell value (A) in learning and the inter-cell value (B) being reproduced.

  Furthermore, if the cell center value used for the slope calculation is expanded to four points on both sides sandwiching the inter-cell value for calculating the phase error, the slope at the inter-cell value time can be calculated with higher accuracy.

  As described above, the reproduction signal gradient (Δv / Δt) in the vicinity of the cell is calculated based on the level information of the cell center value and the cell value reproduced during learning. Then, by applying the gradient (Δv / Δt) and the ideal level (A) of the inter-cell value to the inter-cell value (B) in the actual reproduction signal, the multi-level information recording / reproduction can be performed from the reproduction signal. It becomes possible to extract the phase error signal directly.

  Note that when there is no level difference between two consecutive cell center values or when the level difference is small, the gradient of the reproduction signal is extremely small in the inter-cell value. Therefore, if the phase error is calculated based on this gradient information, the phase error is calculated. The accuracy of the error information is degraded. Therefore, when two consecutive cell center values determined to be during reproduction do not reach a predetermined difference, an operation that does not detect phase error information is also necessary to improve the PLL control accuracy. For example, when the levels V (k−1) and V (k) at the continuous cell center values (k−1, k) have a relationship of | V (k−1) −V (k) | ≦ 3, the phase Processing such as stopping detection of error information is required.

The operation of the actual apparatus using the phase error signal detection method described above will be described below with reference to the drawings and flowcharts. FIG. 11 shows a record information sequence. In the figure,
(A) is a PLL pull-in pattern located at the beginning of the recording data, and this pattern is often used regardless of multi-value recording.
(B) is a recording pattern for learning to obtain the ideal reproduction signal of the known pattern described above.
In (C), user information to be recorded is generated after being subjected to processing such as error correction. Thus, according to the present invention, there is no need for a special insertion pattern for PLL control of the recovered clock.

  The recording operation will be described with reference to the flowcharts of FIG. 11 and FIG. In the figure, when information is recorded, the optical information recording / reproducing apparatus 1 starts a recording operation upon receiving an information recording command.

  First, at the start of recording, a pattern (A) used for pulling in the PLL is generated (step 1).

  Here, regarding the pattern (A) used for pulling in the PLL, a pattern in which frequency and phase error information is obtained by conventional binarization and the PLL is applied is desirable. For example, a pattern in which the entire cell is marked or no mark is present in the cell is repeated regardless of the multi-value recording information sequence. Furthermore, in order to obtain a reproduction signal with a higher signal-to-noise ratio, a pattern in which two cells are all marked and non-marked may be considered, or a pattern composed of a combination of these may be considered.

  Next, a learning pattern (B) of an 8-level multi-value information string is generated, and recording data is added following the PLL pull-in pattern as shown in FIG. 11 (step 2).

  This learning pattern is considered from the combination of preceding and following cell center values, and it is considered that a learning pattern in which at least 64 (8 × 8) patterns or more are combined is necessary.

  Finally, as shown in FIG. 2, for example, the received record information is converted into eight levels every three bits (where modulation, error correction code addition, etc. are performed). .) A recording information sequence (C) shown in FIG. 11 is generated and added as a recording information sequence (step 3).

  The recording information sequence generated as described above is received, and the multi-value information is recorded on the target track on the optical disc 4 which is an optical information medium by using the optical head 5 using the recording pulse sequence corresponding to each multi-level. (Step 4).

  While the recording information continues, steps 1 to 4 are repeated. (Step 5) When all the recording information has been recorded, the recording operation is finished.

  In recent years, address information and the like in a disc is formed by wobbling guide grooves of information recording tracks, and a means for obtaining address information by reproducing the information groove has become mainstream. Many methods that do not need to be added are adopted.

  Next, the procedure for reproducing the multi-value information recorded in this way will be described with reference to FIG.

  The optical information recording / reproducing apparatus 1 starts a reproducing operation when receiving a command for reproducing information.

  As described above, the address information is reproduced from the wobble information or the like, and the target track of the optical disk 4 is searched. First, reproduction of the PLL pull-in area (A) at the head of the information recording unit is started using the optical head 5, and a reproduction clock synchronized with the cell length is generated (step 6).

  Next, the learning pattern is reproduced using the reproduction clock synchronized with the recording cell, and the reproduction signal level for each recording pattern is sampled together with the cell center value and the inter-cell value, and stored in the memory corresponding to each recording pattern. (Step 7).

  Note that, since the reproduction clock at this time can maintain a state synchronized with the reproduction signal by the PLL pull-in pattern, there is no need to perform the reproduction clock phase control. After the PLL pull-in pattern is reproduced, the phase error information is set to “zero”. And sufficient phase accuracy can be obtained by maintaining the PLL state.

  Based on the learning result, the reproduction of the recorded information is started from the reproduction signal. (Step 8) Since the reproduction method of the recorded information is not directly related to this case, individual explanation is omitted.

  At this time, in order to accurately obtain the reproduction information, it is important to maintain and control the reproduction clock so as to be always synchronized with the reproduction signal. For this purpose, as described above, it is necessary to obtain phase error information between the reproduction clock and the reproduction signal.

  Therefore, in the multilevel level determination value of the cell center value sequentially reproduced in step 8, two cell center values that are ideal values stored in the memory by learning from two consecutive determination values, and between them The inter-cell value is selected and read (step 9).

  By using the change between the two cell center values and the inter-cell value between them, the reproduction signal gradient curve in the ideal state at the inter-cell value is calculated as described above, and this reproduction signal gradient curve and the cell at the time of learning are calculated. Phase error information between the reproduction signal being reproduced and the clock is calculated from the interval value and the inter-cell value sampling level in the reproduction signal (step 10).

  At this time, as described above, when the cell center value level is within a predetermined level difference, the process of temporarily stopping the phase error extraction is also performed.

  Based on this phase error information, PLL control is performed to generate a recovered clock. (Step 11) The PLL circuit does not require a special specification, and it is only necessary to optimize the characteristics corresponding to the reproduction signal frequency band, and the description here is omitted.

  During the information reproduction, step 9 to step 11 are sequentially performed, so that phase error information is directly extracted from the reproduction signal and a synchronous clock is continuously generated.

  Further, the above operation is repeated for each series of units of the information recording strings (A), (B), and (C) to reproduce information (step 12).

  Upon completion of the reproduction command, the reproduction operation is terminated.

  With these operations, information can be reproduced without providing a phase error information pattern.

  Note that the phase error information is not only used for generating the recovered clock, but the standard deviation of the phase error information can be used as an index corresponding to jitter in binary reproduction, for example.

  In addition, ideal values, gradients, and other information necessary for phase error detection are derived in advance at the time of product shipment, stored in the memory in response to the level transition of the cell center value, and detected when this memory information and information are reproduced. It is also possible to derive phase error information based on the cell center value and the inter-cell value.

  Further, the phase error information is tabulated in advance, and can be extracted based on the ideal value between cells and the detected value between cells.

1 is a block diagram showing an embodiment of an optical information recording / reproducing apparatus according to the present invention. It is a figure explaining the width | variety of the track direction by the difference in the level of the multi-value information pit concerning this invention, and the combination of 3 bits corresponding to it. It is a figure which shows the relationship between a schematic diagram when a random information pit is recorded with respect to the track which concerns on this invention, and a light spot. The figure explaining the parameter of the optical simulation for demonstrating the reproduction | regeneration principle of this invention. The figure explaining the shape of the information pit given by the optical simulation for demonstrating the reproduction principle of this invention. The figure explaining the reproduction signal with respect to the combination of the information pit written in three continuous cells by the calculation result of the optical simulation for demonstrating the reproduction principle of this invention. The figure which shows the amplitude distribution of the cell median value by the optical system parameter of the optical information recording / reproducing apparatus of this invention. The figure which shows the combination of the amplitude distribution of the value between cells by the optical system parameter of the optical information recording / reproducing apparatus of this invention, and the level of a cell on either side. The figure explaining the positional relationship of the cell and light spot before and behind at the time of sampling the value between cells. FIG. 4 is a reproduction signal change diagram illustrating the phase error detection method of the present invention. The figure explaining the recording information sequence in this invention. The flowchart explaining the information recording of the optical information recording / reproducing apparatus of this invention. The flowchart explaining the information reproduction | regeneration of the optical information recording / reproducing apparatus of this invention. The figure explaining the width | variety of the track direction by the difference in the level of the conventional multi-value information pit. The figure explaining the amplitude distribution of the conventional cell median. The figure explaining the conventional record information sequence.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical information recording / reproducing apparatus 2 Control circuit 3 Spindle motor 4 Optical disk 5 Optical head 6 Optical head control circuit 7 Information recording circuit 8 Information reproducing circuit 9 Spindle motor controller 10 Interface controller 11 Track,
12 Information pit 13 Light spot

Claims (8)

Virtually spaced cells are provided on the track of the optical information medium,
By using a light spot, recording multi-value information by changing the length of the information pit in the track direction or the area of the information pit in the cell, and detecting the level of the multistage reproduction signal from the information pit In an optical information reproducing method for reproducing multi-value information with respect to an optical information medium having a recording / reproducing area for reproducing multi-value information,
Detecting one inter-cell value in two or more consecutive cells in the recording / reproducing area, and two or more cell center values sandwiching the cell;
Based on the difference between the detected inter-cell value and the detected inter-cell ideal value corresponding to the detected cell center value, and the gradient of the reproduction signal in the vicinity of the inter-cell ideal value,
And a step of acquiring phase error information of the reproduction signal.   2. The inter-cell ideal value and the gradient are derived by reproducing a multi-value learning area consisting of information pits for learning recorded at the head of the recording / reproducing area. The optical information reproducing method described.   The optical information reproducing method according to claim 1, wherein the inter-cell ideal value and the gradient are derived by simulation.   The acquisition step calculates the phase error information from the gradient calculated by two or more cell center values sandwiching the inter-cell ideal value and a difference between the inter-cell ideal value and the detected inter-cell value. 4. The optical information reproducing method according to claim 2, wherein the optical information is reproduced.   The acquisition step includes the gradient calculated by the ideal value between cells and two or more cell center values sandwiching the ideal value between cells, and the difference between the ideal value between cells and the detected inter-cell value. 4. The optical information reproducing method according to claim 2, wherein the phase error information is calculated.   The acquired phase error information is tabulated in advance, and is acquired by being extracted based on the ideal value between cells and the detected value between cells. Optical information reproduction method.   2. The optical information reproducing method according to claim 1, wherein in the phase error detection, the extraction of the phase error signal is stopped when the level difference between the cell center values before and after is within a predetermined value. Virtually spaced cells are provided on the track of the optical information medium,
By using a light spot to record multi-value information by changing the length of the information pit in the track direction or the area of the information pit in the cell, and detecting the level of the multistage reproduction signal from the information pit In an optical information reproducing apparatus for reproducing multi-value information with respect to an optical information medium having a recording / reproducing area for reproducing multi-value information,
Detecting means for detecting one inter-cell value in two or more consecutive cells in the recording / reproducing area and two or more cell center values sandwiching the inter-cell;
Based on the difference between the detected inter-cell value and the ideal value between cells corresponding to the detected cell center value, and the gradient of the reproduction signal in the vicinity of the ideal value between cells,
An optical information reproducing apparatus, comprising: an acquisition unit configured to acquire phase error information of the reproduction signal.

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